The present invention relates to pumps, and particularly to pumps for injecting fertilizer or other material into a pressurized water supply line.
Water irrigation systems commonly include pumps for introducing fertilizers, herbicides, and other materials into the irrigating water such that the irrigating water acts both as a conveyor and as a distributor of these materials. This eliminates the need for separately spreading solid or liquid fertilizers or other chemicals over the ground, as well as the possible damage to the soil (by compression) or to the crops that may result from such separate spreading. In addition, distributing these materials via the irrigating water also eliminates the need to purchase, maintain and operate separate equipment for this purpose, and better insures uniformity of distribution of the materials.
A number of devices are known for injecting fertilizers or other materials into the pressurized water supply lines, but the known devices are not entirely satisfactory. One known device includes an arrangement for introducing the materials into the water supply line on the suction side of the pressurizing pump, but such known arrangements are generally cumbersome, difficult to control accurately, and may cause chemical damage to the main pump. Another known arrangement includes a Venturi-type device, but in such arrangement, the injection rate is difficult to control and maintain. A further known arrangement is by the use of by-pass pressure displacement tanks, but such arrangements are also difficult to control and to maintain the injection rate, and also the metal tanks tend to corrode in a chemical environment. A still further known arrangement includes an injector powered by an auxiliary motor, but such devices require a power source energized by fuel or electricity, which is not always available in remote locations of the water supply line; in addition, corrosion is another problem in such arrangements, particularly if the injector is powered by an electric motor.
Also known are hydraulic-powered injectors deriving the energy from the pressurized water in the water supply line; however, the known devices of this type are usually of very complicated construction, which is costly to manufacture and to maintain.
A further known pump, as described in U.S. Pat. No. 3,570,508, includes a propeller immersed in the water of the supply line so as to utilize the energy of the pressurized water for driving the pump. The present invention is directed to the latter type of pump but provides a number of important advantages as will be described more particularly below.
An object of the present invention is to provide a pump, and particularly one of the latter type powered by the pressurized water of the supply line, but of relatively simple construction which can be manufactured and maintained at relatively low cost.